First, we strongly recommended using the synovial α‐defensin ELISA test as a reliable diagnostic test for chronic PJI after excluding the IA diagnosis; while other synovial tests (except synovial IL‐6 and TNF‐α) could also be treated as surrogates if the α‐defensin ELISA test is unavailable in some areas. This evidence concerns the gene TNF and juvenile polyposis syndrome.